I find myself doing the following in photoshop.

• Cleaning up little imperfections with the clone stamp tool.
• Adding a border/frame to the picture.

That's it.

I'm curious what you guys do in photoshop to enhance the quality of your renders?

Hmmmmmm...let's see (adding to your list):

• Creating/adding a background (if not added in Poser)
• Fixing contrast/brightness, hue/saturation, shadows/highlights, etc. if needed
• Adding my signature to the image

Yeh ok, adding to the above:

• Adding lens effects like lens flares, DoF, motion blur, vignetting
• Adding stuff like glows, film grain
• Converting from HDR to LDR and tone mapping
• Combining various layers and passes
• Gamma correcting to whatever display/print device i'll be using

And lets not forget Posers best friend "liquify" for those ugly joints and more.
Don